The present invention relates to a device for delivering sand to a road surface and, more particularly, to a vehicle-mounted device that automatically delivers a traction enhancing material proximate one or more wheels of a vehicle.
In almost all climates, slippery roads pose a potential burden to drivers. In colder climates, ice formation on the roads can create treacherous driving conditions. In warmer weather where icy roads are not an issue, wet roads have a similar albeit reduced adverse effect on tire traction.
Loss of traction due to wet or icy roads is attributable to a change in the coefficient of friction (COF) between the tire and the road surface. On dry roads, the COF is adequate to permit traction for accelerating, decelerating, and turning. However, when the pavement is wet or icy, the COF drops and the vehicle""s performance characteristics become more unpredictable. In particular, the vehicle is more susceptible to tire spin during acceleration and tire lock during braking and turning. Although tire slippage during acceleration is a problem, it does not pose the danger inherent with decreased stopping ability. While the present invention is advantageous during both tire slip (during acceleration) and tire skid (during deceleration) situations, it is directed primarily to a traction enhancing device and method for assisting a vehicle in decelerating and stopping.
Various devices have been developed to improve vehicle traction on ice or other slippery road surfaces. The most common method known is to dispense granular salt or sand directly to the road surface. While effective in providing traction, salt is highly corrosive to vehicles and cumulative use can damage road surfaces. Sand, on the other hand, provides the traction benefits of salt without the harmful side effects.
Sand is typically dispensed by a municipal dump truck, usually following a winter storm. Unfortunately, there is a period of time after the storm in which the roads remain untreated. This is particularly evident on smaller roads and side streets which may not be treated for quite some time. In addition to this delay, sand coverage of a road surface may be spotty due to the operation of conventional sand spreaders. For these reasons, municipal sand dispensing systems are not completely effective.
In an attempt to overcome these problems, sand dispensing systems that attach directly to an automobile have been developed. These systems are advantageous over municipal spreaders in that they are integral to the vehicle. Thus, they can dispense sand at any time and in any place. For example, U.S. Pat. No. 5,118,142 discloses a traction device that disperses sand to the vicinity of one or more tires of an automobile. While effective in delivering sand to the tire/road interface, the ""142 patent requires manual activation and requires a steady stream of delivered sand. Depending on the speed of the car, a large volume of sand may be needed in order to bring the car to a complete stop.
U.S. Pat. No. 5,582,441 discloses another system comprising a sand reservoir incorporated into the front bumper of an automobile. A blower system dispenses the sand in a wide pattern forward of the vehicle. While requiring less sand than other sand dispensing devices, the ""441 system still delivers more sand than is necessary. Stated alternatively, the wide sand dispersion pattern results in excessive sand deposited on the road, some of which is not utilized by the vehicle tires. Additionally, the ""441 patent requires a blower source in order to propel the sand.
Accordingly, the current traction enhancing devices have disadvantages that limit their commercial acceptance. A traction enhancing device that is fully automatic and applies only the amount of traction enhancing material necessary to adequately increase the COF is highly desirable.
A traction enhancing device and method are disclosed. The traction enhancing device, in one embodiment, comprises an air duct for receiving air incident on the vehicle; a storage hopper adapted to hold a traction enhancing material; a valve assembly intermediate the hopper and the air duct wherein the valve assembly selectively permits communication between the hopper and the air duct; and a control system for selectively activating the valve assembly in response to one or more control inputs.
A method of dispensing a traction enhancing material to a road surface generally forward of one or more tires of a moving vehicle wherein the vehicle has an anti-lock brake system is also disclosed. In one embodiment, the method includes collecting air incident on the moving vehicle; accelerating the air through an air duct; sensing a loss of traction between the one or more tires and the road surface beyond a predefined threshold level; selectively dispensing a traction enhancing material into the air duct; and directing the accelerated air and entrained traction enhancing material to the road surface forward of the one or more tires.
In one embodiment, the air duct has an air scoop for receiving air and a nozzle for directing the received air to a tire/road interface. The scoop may also include an elbow intermediate the air scoop and the nozzle.
The hopper may couple to the air duct at an aperture. Furthermore, the aperture may be selectively covered by a valve assembly having a movable valve member.
In another embodiment, a device for distributing a traction enhancing material to a portion of road surface generally forward of one or more tires of a moving vehicle is disclosed. The device includes an air duct defining an interior passageway, wherein the air duct has: a scoop for receiving air incident on the moving vehicle; a nozzle for directing the air to the road surface; and one or more elbows intermediate the scoop and nozzle. The elbow may provide a smooth transition for air traveling from the scoop to the nozzle. The device may also include a storage hopper adapted to store a volume of traction enhancing material wherein the hopper has an outlet channel. Additionally, the apparatus includes a valve assembly for selectively opening and closing an aperture defined by an intersection of the outlet channel and the air duct. The valve assembly permits movement of the traction enhancing material from the hopper to the air duct where it becomes entrained with the air. Furthermore, the apparatus includes a control system for selectively activating the valve assembly in response to one or more control inputs.
In yet another embodiment, the scoop has a flared mouth and is located slightly forward of the front end of the vehicle. The interior passageway may have a reduced diameter and the nozzle may include an enlarged, annular portion and an internal tubular portion. The internal tubular portion may have one or more openings that permit the air to expand from the tubular portion into the annular portion but prevent the passage of the traction enhancing material from the tubular portion into the annular portion. In one embodiment, the openings are holes. In another embodiment, the openings are slots.
The hopper may have a removable cover and a level sensor. Proximate the channel and aperture, the hopper may also include a heat trace to prevent freezing of the traction enhancing material.
The control system may include a microprocessor-based module for receiving and processing the control inputs. It may also have a first control output for selectively opening and closing the valve assembly in response to the control inputs and a second control output for selectively aiming the nozzle. The controller may monitor various control inputs including one or more accelerometers operatively connected to the control system; one or more wheel speed sensors operatively connected to the control system and one or more steering wheel position sensors operatively connected to the control system.
In yet another embodiment, an apparatus for distributing a traction enhancing material to a portion of road surface generally forward of one or more tires of a moving vehicle is described. The apparatus comprises a source of compressed gas; and a discharge unit, wherein the discharge unit can selectively discharge a projectile to the road surface and wherein the discharge unit develops energy from the source of compressed gas.
In still yet another embodiment, the method may include intermittently rotating the tire in response to the anti-lock brake system, thereby trapping a traction enhancing material between a tire and a road surface and thus increasing traction.
In another embodiment, a method of dispensing a traction enhancing material to a portion of road surface generally forward of one or more tires of a vehicle having an anti-lock brake system is disclosed wherein the method comprises determining a wheel speed; determining a ground speed; comparing the wheel speed to the ground speed; opening a valve in proportional response to the ground speed; dispensing a traction enhancing material through the valve; determining when the ground speed matches the wheel speed; and closing the valve.
Accordingly, the present invention provides an effective traction device that can be used on a variety of vehicles. By taking advantage of the vehicle anti-lock brake system, the present invention may provide improved traction with minimal dispersion of sand. Additionally, the present invention takes advantage of air incident on the vehicle rather than a separate power source to disperse the traction enhancing material. Furthermore, the system is fully automatic and requires no driver input in order to operate.